Parker and Model 21 vent ribs are of the same design in appearance. The frame is humped up a little at the breech and the rib runs fairly level to be low at the muzzle, not exactly parallel to the bores but not way up in the air. They are the best looking vent ribs. The Italian Berettas, the Galazan RBL, and the AYA are too low to perform the job that a vent rib is designed for, dissipation of heat waves. I see no problem with the vent rib on my 26" Parker in the field as long as I keep the underside wet with oil. Most older guns are brown with rust underneath the rib, but a spray with oil now and then keeps it from being a problem.
